1. Field of the Invention
The invention relates to an installation for generating superheated process steam from salt-containing raw water, using preheaters for heating the raw water.
2. Description of the Prior Art
For generating superheated steam for steam turbine installations there is employed, as a rule, a high-pressure steam generator (German Published Non-Prosecuted Application 22 43 380) in which a closed water-steam circuit is provided. In this water-steam circuit, high-quality feedwater is used which is kept free of salt and other impurities by processing and filter equipment. Contrary thereto, in chemical operations for coal gasification, in raw-oil pumping or in the processing of oil sand or oil shale, process steam is required which is not fed back into the installation. This means that, for generating superheated process steam for such purposes, large quantities of feedwater must be processed and desalinated, because otherwise salt deposits must be expected, particularly in the evaporation zone, which degrade the heat transfer and cause corrosion of the evaporator tubes.